Sec Form 4 Filing - WHEELER CRAIG A @ MOMENTA PHARMACEUTICALS INC - 2020-05-07

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person WHEELER CRAIG A 2. Issuer Name and Ticker or Trading Symbol MOMENTA PHARMACEUTICALS INC [ MNTA] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) President & CEO (Last) (First) (Middle) C/O MOMENTA PHARMACEUTICALS, INC., 301 BINNEY STREET 3. Date of Earliest Transaction (MM/DD/YY) 05/07/2020 (Street) CAMBRIDGE, MA02142 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 05/07/2020 M( 1 ) 5,782 A 14,521 ( 7 ) D Common Stock 05/08/2020 S( 3 ) 2,602 D $ 32.94 ( 4 ) 11,919 D Common Stock 36,725 I Craig A Wheeler 2016 Annuity Trust Common Stock 48,263 I Craig A Wheeler 2018 Annuity Trust Common Stock 474,598 ( 8 ) I Craig Wheeler Revocable Trust

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares Restricted Stock Units ( 5 ) 05/07/2020 M( 1 ) 5,782 ( 6 ) ( 6 ) Common Stock 5,782 $ 0 17,344 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other WHEELER CRAIG A C/O MOMENTA PHARMACEUTICALS, INC. 301 BINNEY STREET CAMBRIDGE, MA02142 X President & CEO Signatures /s/ R. Mark Chamberlin as attorney in fact 05/11/2020 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Shares received pursuant to settlement of Restricted Stock Units that were granted on February 7, 2017. ( 2 )Restricted Stock Units convert into common stock on a one-for-one basis. ( 3 )This transaction was effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on August 7, 2017. ( 4 )This transaction was executed in multiple trades at prices ranging from $32.70 to $33.42. The price reported above reflects the weighted average sale price. The reporting person hereby undertakes to provide upon request to the SEC staff, the issuer or a security holder of the issuer full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote. ( 5 )Each Restricted Stock Unit represents a contingent right to receive one share of MNTA common stock. ( 6 )Subject to the officer's continued employment with the company, the restricted stock units will vest with respect to 25% of the shares on the first anniversary of the grant date, and the remainder will vest in equal quarterly installments over the subsequent three years. ( 7 )Reflects a decrease of 45,925 shares of MNTA common stock transferred to the Craig Wheeler Revocable Trust on April 17, 2020. ( 8 )Reflects the transfer of 45,925 shares of MNTA common stock on April 17,2020 that were previously held in the Craig A. wheeler personal account.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

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